| Discovery | |||||||
|---|---|---|---|---|---|---|---|
| Discovered by | Philip D. Nicholson, Brett J. Gladman, Joseph A. Burns, John J. Kavelaars using the Hale telescope | ||||||
| Discovered in | September 6, 1997 | ||||||
| Orbital characteristics | |||||||
| Mean radius | 12,179,000 km | ||||||
| Eccentricity | 0.5224[1] | ||||||
| Orbital period | 1288.28 d | ||||||
| Inclination | 159° (to the ecliptic)[2] | ||||||
| Is a satellite of | Uranus | ||||||
| Physical characteristics | |||||||
| Mean diameter | ~150 km (estimate)[2][3] | ||||||
| Surface area | ~70,000 km² (estimate) | ||||||
| Volume | ~1,800,000 km³ (estimate) | ||||||
| Mass | ~2.3 × 1018 kg (estimate) | ||||||
| Mean density | ~1.3 g/cm³ (assumed) | ||||||
| Surface gravity | ~0.040 m/s2 (estimate) | ||||||
| Escape velocity | ~0.064 km/s (estimate) | ||||||
| Rotation period | ? | ||||||
| Axial tilt | ?° | ||||||
| Albedo | 0.04 (assumed)[2][3] | ||||||
| Surface temp. |
| ||||||
| Atmospheric pressure | 0 kPa | ||||||
Sycorax (pronounced /ˈsɪkɵræks/ SIK-or-aks) is the largest retrograde irregular satellite of Uranus. Sycorax was discovered on 1997-09-06 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale telescope, together with Caliban and given the temporary designation S/1997 U 2.[4]
Officially confirmed as Uranus XVII, it was named after Sycorax, Caliban's mother in William Shakespeare's play The Tempest.
Orbit 
Sycorax follows a distant orbit, more than 20 times further from Uranus than the furthest regular moon Oberon. Its orbit is retrograde, moderately inclined and eccentric. The orbital parameters suggest that it may belong, together with Setebos and Prospero, to the same dynamic cluster, suggesting common origin.[5] The diagram illustrates the orbital parameters of the retrograde irregular satellites of Uranus (in polar co-ordinates) with the eccentricity of the orbits represented by the segments extending from the pericentre to the apocentre.
Physical characteristics
The diameter of Sycorax is estimated at 150 km (assuming albedo of 0.04)[2][3] making it the largest irregular satellite of Uranus, comparable in size with Himalia, the biggest irregular satellite of Jupiter.
The satellite appears light-red (colour indices B-V=0.87 V-R=0.44,[6] B-V=1.01 V-R=0.48[7]) redder than Himalia but still less red than most Kuiper Belt Objects.
The rotation period could not be estimated conclusively (best fit ~4 h).[7]
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